1 1. Field of the Invention
The present invention relates to a line switching control system for effecting line switching between a facsimile communication mode or a data communication mode and a voice communication mode in mobile communication, particularly mobile telephone service where a facsimile or a data terminal is added to an automobile telephone unit.
2. Description of the Prior Art
As social and economic activities are more and more complicated and diversified, there are demands for increased capacity and improved quality of electronic communication services.
Mobile communication plays an important role as it allows users to communicate anytime and anywhere.
Particularly, the mobile communication system has already entered the commercial stage in various countries such as the U.S.A., Japan, and European countries. Moreover, data communication and facsimile communication have also started to be available in the mobile communication, especially, the mobile telephone network.
Since the market for such new communication service has not yet been full-fledged, it is the current practice to carry out data communication through the mobile telephone-network by either effecting switching between a data mode or a voice mode with a manual switch associated with a modem or performing mode switching with the switch of a switch box coupled between an mobile telephone set and a modem. The latter switching arrangement is employed for facsimile communication.
For data or facsimile communication using a general telephone network, it is customary to attach an NCU(Network Control Unit) to a modem or assemble the NCU in the modem, and to effect channel switching between data and facsimile modes with a manual switch having an NCU function.
However, where data or facsimile communication is to be carried out using the mobile telephone network, since no device with the above control function is available now, switching has to be controlled only by the manual switch of a modem or a switching box between the modem or facsimile and the mobile telephone set.
At present, priority is given to the installation of an mobile telephone unit in an automobile, and a modem or switching box, as referred to above, is often located in a place remote from the user (such as at the assistant driver's seat or the dashboard in front of the assistant driver's seat). Consequently, the user or driver must reach for the switch or move to the modem or switching box for the access to the switch.
When there is an incoming call while the automobile is running, the call cannot be answered by the driver since accessing the switch at such a time is extremely dangerous.